Dipol pętlowy

Antenna type loop loop

Dipole dipole - an antenna constructed of two parallel dipoles fed in the middle of one of them. The radiation characteristics of the loop dipole are similar to the corresponding straight dipole. The difference in the vertical plane is that instead of uniform radiation in all directions, there is an increase in gain on the side of the power element. In the horizontal plane a slightly "shallower" radiation minima can be observed. The deformation distortion is the greater the greater the distance between the dipole elements. This is because the side connections function as additional short antennas.

Differences are also in the distribution of current along the dipole. Since the two parts of the dipole are connected together (closed circuit), non-zero currents appear at the ends of the arms. Due to the voltage distribution and currents in the loop dipole, it can be grounded in the middle to protect the connected equipment from electrostatic charges.

The input impedance of the loop dipole is approximately 280 Ω, which is four times greater than the impedance of a straight dipole, due to the strong coupling between the component dipoles and the impedance transformation. This allows you to power it directly from the symmetrical line (300 Ω impedance cable).

The loop dipole usually occurs as an active element in Yagi-type antennas. The loop of the loop dipole is wider than the simple dipole.

After rolling the loop dipole into an open ring, a ring dipole of approximately omnidirectional characteristic is obtained. This antenna has a gain of -3 dB, which can be compensated by placing several such dipoles over a distance of 0.5 λ from each other. Bibliography

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